Heat-tolerant hot pepper exhibits constant photosynthesis via increased transpiration rate, high proline content and fast recovery in heat stress condition

Sherzod Nigmatullayevich Rajametov,Eun Young Yang,Soo Young Chae,Hyo Bong Jeong,Myeong Cheoul Cho,Won Byoung Chae

doi:10.1038/s41598-021-93697-5

Sherzod Nigmatullayevich Rajametov, Eun Young Yang + Show 4 more

Open Access

https://doi.org/10.1038/s41598-021-93697-5

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Abstract

Understanding the mechanism for heat tolerance is important for the hot pepper breeding program to develop heat-tolerant cultivars in changing climate. This study was conducted to investigate physiological and biochemical parameters related to heat tolerance and to determine leaf heat damage levels critical for selecting heat-tolerant genotypes. Seedlings of two commercial cultivars, heat-tolerant ‘NW Bigarim’ (NB) and susceptible ‘Chyung Yang’ (CY), were grown in 42 °C for ten days. Photosynthesis, electrolyte conductivity, proline content were measured among seedlings during heat treatment. Photosynthetic rate was significantly reduced in ‘CY’ but not in ‘NB’ seedlings in 42 °C. Stomatal conductivity and transpiration rate was significantly higher in ‘NB’ than ‘CY’. Proline content was also significantly higher in ‘NB’. After heat treatment, leaf heat damages were determined as 0, 25, 50 and 75% and plants with different leaf heat damages were moved to a glasshouse (30–32/22–24 °C in day/night). The growth and developmental parameters were investigated until 70 days. ‘NB’ was significantly affected by leaf heat damages only in fruit yield while ‘CY’ was in fruit set, number and yield. ‘NB’ showed fast recovery after heat stress compared to ‘CY’. These results suggest that constant photosynthetic rate via increased transpiration rate as well as high proline content in heat stress condition confer faster recovery from heat damage of heat-tolerant cultivars in seedlings stages.

Highlights

Understanding the mechanism for heat tolerance is important for the hot pepper breeding program to develop heat-tolerant cultivars in changing climate
Plant height and shoot and root fresh weight were significantly reduced in seedlings grown in 42 °C compared to normal temperature regardless of heat-tolerant or susceptible cultivars (Supplementary Table S1)
Chlorophyll content significantly decreased as days of heat treatment (HT) increased in both cultivars (Supplementary Fig. S1) and the decrease was more prominent in a heat-susceptible cultivar, ‘Chyung Yang’ (CY)’, than ‘NB’, after 2nd day of HT the difference was not significant

Summary

Introduction

Understanding the mechanism for heat tolerance is important for the hot pepper breeding program to develop heat-tolerant cultivars in changing climate. ‘NB’ showed fast recovery after heat stress compared to ‘CY’ These results suggest that constant photosynthetic rate via increased transpiration rate as well as high proline content in heat stress condition confer faster recovery from heat damage of heat-tolerant cultivars in seedlings stages. A lot of screening methods for identifying heat-tolerant genotypes in different developmental stages and day and/or night temperatures have been developed for various crops in Solanaceae family[4,6,9,12,15]. Breeding programs should focus on determining developmental stages susceptible to heat stress -to develop hot pepper cultivars with heat tolerance. Plants are usually susceptible to high temperature in early growth stages and, seedlings in the appropriate stage for transplanting can be proper starting materials to reveal heat tolerance mechanism in hot pepper

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